Reporter molecules are routinely used to monitor molecular events in the fields of biology, biochemistry, immunology, cell biology, and molecular biology. Luciferases based on the luciferase secreted from the deep-sea shrimp, Oplophorus gracilirostris, may be used as reporter molecules and have been shown to have advantageous characteristics including broad substrate specificity, high activity, and high quantum yield. It may be further advantageous, in certain applications, to control the luminescent signal from Oplophorus luciferases.